Abstract

Long Island, New York (Figure 1) extends for about 120 miles in a general east-west direction off the southern portions of the States of New York and Connecticut, from which it is separated by Long Island Sound. The western end of the island contains the Counties of Brooklyn and Queens which are part of New York City. To the east are the Counties of Nassau and Suffolk. The surface geology of Long Island is mostly of glacial origin. That portion of the south shore of Long Island with which this paper is concerned (Figure 2) consists of outwash plains of sand and gravel fringed by barrier beaches from 600 feet to 3,500 feet in width. They rise to about 15 feet above mean sea level, and in their natural condition are more or less protected by sand dunes which may reach an elevation of from 25 feet to 30 feet. The sand along the foreshore is predominantly quartz, averaging about 0.4 mm. at mid-tide level, and becoming somewhat finer offshore. The foreshore slope of the beaches averages about 1 on 10 above the mean low water line and about 1 on 30 immediately offshore. Several hundred feet offshore the slope flattens to about 1 on 250.